[datatable-help] problems with adding a DateTime column

[Matthew Dowle]

Ah, we crossed emails. It's been reported (to me offlist) that POSIXct may
be working in keys, in integer form without any fractional seconds I
guess. Worth a try.

> Try as.IDate around your strptime.  strptime returns POSIXlt which
> isn't really amenable to data tables (or frames for that matter).  In
> base R you would usually convert to POSIXct, but IDate is integer
> based and made to be able to key on dates in data.tables.
>
> On Thu, Mar 8, 2012 at 11:11 AM, Alexander Peterhansl
> <APeterhansl at gaincapital.com> wrote:
>> Dear Datatable-Help:
>>
>> I’m running R version 2.14.1 and data.table 1.7.10 (on Windows 7 and
>> Linux).  On both systems I get a strange result in the following toy
>> example:
>>
>>
>>
>> test <- data.table(A=c(1,2,3))
>>
>> test[,B:= c("2011-01-01","2011-01-02","2011-01-03")]
>>
>> test[,C:=
>> strptime(c("2011-01-01","2011-01-02","2011-01-03"),format="%Y-%m-%d")]
>>
>> Output:
>>
>>       A          B       C
>>
>> [1,]   1 2011-01-01 0, 0, 0
>>
>> [2,]   2 2011-01-02 0, 0, 0
>>
>> [3,]   3 2011-01-03 0, 0, 0
>>
>>
>>
>> Columns A and B show the expected behavior.  Column C was supposed to
>> simply
>> convert the date strings into DateTime types.  Clearly this is not
>> happening.
>>
>>
>>
>> Please help.
>>
>> Regards,
>>
>> Alex
>>
>>
>>
>>
>>
>>
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